Apparatus for reducing the atmospheric oxygen content of fluent solid pourable materials by gas exchange

ABSTRACT

To prevent spoiling of fluent solid materials by the action of atmospheric oxygen entrapped in the material during the packaging thereof in a form, fill and seal machine, the materials are subjected to a counterflow treatment with a gas which will take up the oxygen. For this purpose there is a gas supply conduit opening into the zone of the materials in the feed pipe of the machine, and a gas-storage chamber in the forming mandrel of the machine above this zone.

United States Patent [72] Inventors Norbert Buchner Beutelsbach, Wurttemberg; Klaus Domke, Stuttgart-Weilimdorf, Germany [21 Appl. No. 848,479 [22] Filed Aug. 8, 1969 {45] Patented May 25, 1971 [73] Assignee Fr. Hesser Maschienfabrik Aktiengesellschaft Stuttgart-Bad Cannstatt, Germany [32] Priority Aug. 22, 1968 [33] Germany [31] P 17 86 137.9

[52] US. Cl

[51] lnt.Cl B6Sb31/04 [50] Field ofSearch 53/112 [56] References Cited UNITED STATES PATENTS 2,160,367 5/1939 Maxfield 53/112(X) 3,482,373 12/1969 Morris 53/112 Primary ExaminerTravis S. McGehee Att0rney-Waters, Roditi, Schwartz & Nissen ABSTRACT: To prevent spoiling of fluent solid materials by the action of atmospheric oxygen entrapped in the material during the packaging thereof in a form, fill and seal machine, the materials are subjected to a counterflow treatment with a gas which will take up the oxygen. For this purpose there is a gas supply conduit opening into the zone of the materials in the feed pipe of the machine, and a gas-storage chamber in the forming mandrel of the machine above this zone.

PATENTED umzslan 3'; 579,945

saw 1 or z APPARATUS FOIR REDUCING BACKGROUND-FIELD OF THE INVENTION Application for US. Pat. Ser. No. 707,843, filed Feb. 23, 1968 and entitled Reducing the atmospheric oxygen content of bulk materials which can flow or be trickled" describes a method and apparatus for the stated purpose in which a suitable protective gas which combines with atmospheric oxygen is conducted in counter current through a confined passageway. By this method, and using the means for performing the same disclosed in the aforesaid patent application, atmospheric oxygen present in the pourable material can be removed by comparatively simple means to a degree sufficient to fully and adequately protect the material concerned from premature deterioration.

When using this method in connection with machines in which packages are produced substantially at the same time that they are filled, as for example is the case in so-called tubular bagmaking machines, it has been found that small amounts of atmospheric oxygen can reenter the package because of the fact that, when a length of tube is drawn down for each successive bag, hollow spaces are formed into which atmospheric air can penetrate because of the drop in pressure,-and moreover that when the machine is started up there are indeterminate quantities of air present particularly in the first bag and in the filling pipe.

It is an object of the present invention to apply the oxygen extraction by protective gas counterflow principle to this particular situation.

SUMMARY OF THE INVENTION To this end the machine is provided with a conduit connected to a supply of the oxygen-extracting protective gas and disposed so as to discharge into the forming mandrel of the machine in the zone of the lower end of the filling pipe, and there is a hollow chamber, open at its upper end, communicating with the end of said mandrel, and sewing as a gas storage means, provided in the mandrel above the gas discharge from said conduit. The volume of hollow gas-storage chamber is at least as large as the volume of gas required for each draw down of the tube, less the quantity of gas which is supplied through the gas supply conduit during the draw down operatron.

The above said hollow chamber may be defined by the spacing between the filling pipe and the larger diameter mandrel which surrounds it. This provides a chamber of annular cross section, of selectable height, and open at the top.

In order, as far as possible, to prevent turbulence in the gas column which is created in this hollow storage chamber and moves up and down in rhythm with the drawing down of the individual bags, a number of axial parallel and radially disposed plates can be provided within this hollow chamber to bring about a laminar type of gas flow.

With the arrangement of the present invention, the filling system can be freed of atmospheric air in simple fashion before the machine is started up, without the end of the packaging tube which has been closed in the last working stoke of the machine having to be opened, as is the case in known machines of this kind. The continuous supply of gas in the vicinity of the outlet of the filling pipe effectively prohibits any entry of atmospheric oxygen into the filling system. The gas column which forms above the gas inlet provides for a simple, virtually pressure-free gas supply to the bags which would otherwise only be obtainable with very expensive regulating devices, so that this gas supply neither inflates the bag nor imposes any additional strain on the closure seams of the bug by reason of gas pressure.

BRlEF DESCRIPTION or THE nnxwmos Embodiments of the invention are illustrated by way of example in reference to the accompanying diagrammatic drawings in which:

FIG. 1 shows an apparatus in accordance with the invention in conjunction with a plate dispensing machine,

FIG. 2 is a cross section in the plane ll-Il of FIG. 1,

FIG. 3 shows a further embodiment of the apparatus, similar to that of FIG. 1, in conjunction with a weighing device, and

FIG. 4 is a cross section in the plane IV-IV of FIG. 3.

DETAILED DESCRIPTION OF THE DRAWINGS The apparatus illustrated in FIG. 1 comprises a discharge hopper 2 provided with a feed pipe 1 which may be incorporated therein one or more conducting cones, one being shown at 6. Provided in the wall of the pipe I are nozzle openings 4 through which a suitable flushing or protective gas which will take up oxygen, for example carbon dioxide or nitrogen, is introduced into the feed pipe, this gas then passing substantially vertically upwards in counter current through the pourable material which is flowing downwards in pipe 1. The material is thereby freed of the atmospheric oxygen trapped in it. The gas is fed through a pipe 7 to an annular channel 8 which distributes it to the various nozzle openings 4.

Adjoining the lower end of feed pipe 1 is a gastight housing 30 in which is arranged a plate dispensing device 31 of a known type. Gastightly connected to the housing 30 below the discharge point of this plate dispensing device 31 is a pipe 32 which projects into the forming tube or mandrel 22 of a known type of machine for making bags from a tube of packaging material.

This machine, which is denoted 33, works with at least one continuous web of packaging material 34 which is first conducted over the shoulder 20 of the forming mechanism and is thereby applied around the forming tube or mandrel 22 and made into an endless tube 36 of packaging material through the agency of a heat sealing tool 35. The so-formed tube of packaging material is drawn down intermittently from the forming tube 22 by means of a transverse sealing and severing assembly 37, charged during this operation through filling pipe 32, and finally transversely sealed above the top of the filling therein and cutoff so as to form a filled and closed bag package 38, the leading end of the remainder of the tube 36 of packaging material being transversely sealed at the same time.

The filling pipe 32 projecting into the former tube 22 preferably tenninates in the vicinity of the lower end of this tube 22, particularly when this pipe is of comparatively large cross section.

A further and larger diameter pipe 41, arranged around the filling pipe 32, is used to supply the gas for protecting the contents of the bags, which gas also serves for flushing, this pipe 41 being connected to a tubular conduit 25. The hollow annular chamber 23 interposed between the pipe 41 and the forming tube 22 is divided up by a number of plates 39 extending axially and parallel relative to one another, and the lower part of pipe 41 terminates in the vicinity of the outlet from the filling pipe 32 in a number of downwardly directed nozzles 42.

The protective gas which is fed through the tubular conduit 25 emerges from the nozzles 42 and passes into the hollow space in the tube 36 of packaging material located above the transverse seal in the latter. This produces a column of gas in the annular hollow chamber 23, and the volume of this must be so chosen, by appropriate dimensioning of this chamber, that it is sufficient, taken in conjunction with the gas which is continuously fed through nozzles 42, to cover the gas requirement which is created each time a length of bag is drawn down. During successive arrest of the packaging tube 36, the further gas which has been fed in rises again into the hollow chamber 23 in the forming tube, thus creating a fresh gas supply. The effect of plates 39 is that the flow of gas which is occasioned by this, and during the depression of the gas column, remains laminar, wherefore eddies, which could bring about admixing of the upper layer of gas with atmospheric air, are avoided.

In the case of very flat and small bag cross sections two pipes, disposed at the right-hand and the left-hand side of the filling pipe, can be used in the forming tube for gas storage,

thereby enabling the cross section of the forming tube to be kept correspondingly flat.

To provide for continuous supervision of the composition of the gas passing into the bags, it is expedient to use a gas analyzer 43, the probe 51 of which will conveniently extend into the hollow space in the tube above the transverse sea]. This gas analyzer might also be used for automatic control of a regulator 44 which governs the supply of the protective gas through conduit 25.

in the embodiment of the invention illustrated in FIG. 3 a weighing device is used for dispensing. One or more discharge weighers 46 of known type are disposed in housing 45 which is gastight or closed. The appropriate gas is fed in through the nozzles 4 of a nozzle stem 47. The discharge of the batches of pourable material measured out in the weighers again takes place through the filling pipe 32 mounted within the forming mandrel tube 22. 1

To provide for filling of very large bags in an atmosphere of protective gas, provision is made in this embodiment of an additional gas storage device 48 which is arranged externally of the forming tube and comprises a plurality of channels 50 which are arranged parallel with one another.

A gas analyzer may also be provided in this instance, and it is also possible, in this and the other form of construction, to arrange a second gas analyzer 43 in the housing of the dispensing device to control the gas flushing operation during the feed of the pourable material to the dispensing device and, possibly, to automatically control a regulator 44 incorporated in the gas conduit 7.

To free the complete dispensing and filling system of atmospheric oxygen, which is particularly necessary when the machine is first brought into use, or is restarted after a shutdown or pause in the operation, all that is required is to connect the gas supply 25 for a short period before the machine is put into operation to scavenge the atmospheric oxygen present in the hollow space in the packaging tube from the openings of the gas supply device and, on the other hand, to flush the filling pipe through to the dispensing device and the material fed to the latter, this action being aided, if required, by simultaneous opening of the gas conduit 7 into the feed of the pourable material.

It is to be pointed out that the invention is not limited to the specific embodiments which have been described above. it is, for example capable of use in filling systems in which atmospheric oxygen admixed in the pourable material is removed by appropriate means other than flushing by means of gas or in which the pourable material is already oxygen free when it is introduced.

We claim:

1. In a bagmaking machine comprising a former, a hollow mandrel disposed within said former, means for drawing a web of packaging material over said former and between the latter and the mandrel to deform the web into tubular form means for longitudinally closing the tube of packaging material so formed, and a filling pipe projecting into. said mandrel for depositing material to be packaged into said tube, the improvement comprising apparatus for reducing the atmospheric oxygen content of fluent pourable solid material deposited into said tube said apparatus comprising means for passing a protective gas, which is adapted to take up atmospheric oxygen in said pourable material, in counterflow through said material in loose condition, said means comprising a conduit connected to a supply of the protective gas and disposed so as to discharge into said mandrel in the zone of the lower end of the filling pipe, and further means defining a hollow chamber, open at its upper end, communicating with the end of said mandrel and serving as means for reversing and storing the flow of said gas, said further means being provided in the mandrel above the gas discharge from said conduit, said hollow chamber having a predetermined volume sufficient for accommodating the volume of gas necessary for each drawing operation of the tube of packaging material less the amount of gas discharged through said gas conduitduring each drawing operation.

2. An apparatus according to claim 1, in which the mandrel is of larger diameter than the filling pipe and is mounted concentrically around the latter with an annular clearance between them, said clearance forming the said hollow chamber.

3. An apparatus according to claim 2, in which the hollow chamber is divided by a plurality of axially parallel plates disposed radially in relation to said filling pipe.

4. An apparatus according to claim 1, in which the said gas supply conduit is a pipe surrounding the filling pipe and including a plurality of downwardly directed discharge nozzles at the lower end thereof.

5. An apparatus according to claim 1, in which an additional gas-storage device is arranged externally of the forming mandrel and is connected to the aforesaid hollow chamber.

6. An apparatus according to claim 1, in which a gas analyzer is mounted externally of the fonning mandrel and includes a probe extending below said forming mandrel, thereby to project into the hollow interior of a tube of packaging material passing downwards below the forming mandrel and communicating with said hollow chamber.

7. An apparatus according to claim 6, in which the gas analyzer is connected to a regulator for controlling the gas fed to said gas supply conduit in accordance with the gas values measured by said analyzer.

8. An apparatus according to claim 1, wherein said apparatus is constituted by a self-enclosed unit including a device for dispensing the fluent solid material to the bagmaking machine, a device for feeding said material to the dispensing device, and an assembly for flushing the infed material with protective gas.

9. An apparatus according to claim 8, in which said unit includes a conduit through which protective gas is supplied to said device for feeding fluent, solid pourable material to the dispensing device, a gas regulator in the conduit, and a gas analyzer associated with said dispensing device and adapted to test the gas therein and control said gas regulator.

10. Apparatus according to claim 1 wherein the gas supply conduit surrounds said filling pipe.

11. Apparatus according to claim 10 wherein said hollow chamber is annular and surrounds said gas supply conduit. 

2. An apparatus according to claim 1, in which the mandrel is of larger diameter than the filling pipe and is mounted concentrically around the latter with an annular clearance between them, said clearance forming the said hollow chamber.
 3. An apparatus according to claim 2, in which the hollow chamber is divided by a plurality of axially parallel plates disposed radially in relation to said filling pipe.
 4. An apparatus according to claim 1, in which the said gas supply conduit is a pipe surrounding the filling pipe and including a plurality of downwardly directed discharge nozzles at the lower end thereof.
 5. An apparatus according to claim 1, in which an additional gas-storage device is arranged externally of the forming mandrel and is connected to the aforesaid hollow chamber.
 6. An apparatus according to claim 1, in which a gas analyzer is mounted externally of the forming mandrel and includes a probe extending below said forming mandrel, thereby to project into the hollow interior of a tube of packaging material passing downwards below the forming mandrel and communicating with said hollow chamber.
 7. An apparatus according to claim 6, in which the gas analyzer is connected to a regulator for controlling the gas fed to said gas supply conduit in accordance with the gas values measured by said analyzer.
 8. An apparatus according to claim 1, wherein said apparatus is constituted by a self-enclosed unit including a device for dispensing the fluent solid material to the bagmaking machine, a device for feeding said material to the dispensing device, and an assembly for flushing the infed material with protective gas.
 9. An apparatus according to claim 8, in which said unit includes a conduit through which protective gas is supplied to said device for feeding fluent, solid pourable material to the dispensing device, a gas regulator in the conduit, and a gas analyzer associated with said dispensing device and adapted to test the gas therein and control said gas regulator.
 10. Apparatus according to claim 1 wherein the gas supply conduit surrounds said filling pipe.
 11. Apparatus according to claim 10 wherein said hollow chamber is annular and surrounds said gas supply conduit. 